//随机banner数组,图片可以换成图床链接，注意最后一条后面不要有逗号
var bannerimg =[
    "url(/img/dark.jpg)",
    "url(/img/kid.jpg)",
    "url(/img/mood.jpg)",
    "url(/img/c1.jpeg)",
    "url(/img/c4.jpeg)",
    "url(/img/c6.jpeg)"
];
//获取banner图片总数，生成随机数
var bannerindex =Math.ceil(Math.random() * (bannerimg.length-1));
//重设banner图片
document.getElementById("body-wrap").style.backgroundImage = bannerimg[bannerindex];
